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Orthopedic and Rehabilitation Engineering

Orthopedic and Rehabilitation Engineering Lightning Talks

Usability of a Self-stretching Passive Finger/Wrist Device for Chronic Stroke Patients with Spasticity

Saturday, October 26, 2024

9:33 AM - 9:40 AM EST

Location: Room 339

Presenting Author(s)

Jacob Kim (he/him/his)

Student Researcher
Department of Neuroscience, University of Pennsylvania
Philadelphia, Pennsylvania, United States

Co-Author(s)

Reem Azar, MS

PhD Student
University of Pennsylvania, United States

Primary Investigator(s)

Michelle Johnson, PhD (she/her/hers)

Associate Professor
University of Pennsylvania
philadelphia, Pennsylvania, United States

Introduction: With medical inaccessibility on the rise alongside healthcare costs, many stroke patients are unable to receive traditional care or proper physical rehabilitation. 75% of stroke survivors develop hemiplegia affecting the contralesional upper and lower limbs. One of the common symptoms is hypertonicity – an abnormal stiffness of the muscles that lead to spasticity after prolonged muscle contraction. Although treatment options in the form of physical therapy and stretching exist, many patients do not receive sufficient time in supervised therapy to elicit significant effects. Robot assisted therapy, while viable, often tends to be costly and difficult to operate on their own. One such solution is the use of self-operated passive stretching devices that can be operated with minimal or no assistance at a low cost. The goal of this project was to develop and evaluate a new self-stretching finger/wrist device using an iterative design cycle. Early and late-stage device prototypes of the wrist stretching device were evaluated and user experiences were reported.

Materials and

Methods: Early and late-stage prototypes of the device were developed (Figure 1A and 1B). Both prototypes shared the same concept and purpose of manual wrist and finger stretching through the use of self-operated mechanical and pneumatic mechanisms.

To stretch the wrist, we relied on a rotation system with the wrist joint positioned at the center of the rotating dial; users could push the dial and secure it at a suitable stretch angle (Figure 1A). To stretch the fingers, we relied on an inflatable grip that would expand inside the user’s hand -- controlled by a hand pump (Figure 2B).

Although the two stages of the prototypes shared the same fundamental design principles, changes were made to address user experience. First, five healthy controls tested the early stage prototype in the form of putting their arms into the device, using it to stretch the wrist/fingers, and taking their arm off the device. Then, users were asked to rate their experience on a scale of 1-10 in criterias in overall comfort (10 - device is suitably comfortable), unexpected pain (10 - pain present), upper arm muscle tension (10 - abnormal tension in the upper arm), and device security of the arm (10 - arm secured properly for stretching). After, design changes were made to address reported issues and the late stage prototype was made and tested using the same methods with a different group of five healthy controls.

Results, Conclusions, and Discussions: The early stage prototype had an average assessment value of 2.6 comfort, 0.4 pain, 7.6 muscle tension, and 2.6 device security (Figure 4A). General feedback pointed towards the fact that although the device did not cause pain, it was not comfortable and caused too much uncomfortable muscle tension in the upper arm without securing the arm properly. To address these changes, 3 new modules were added. Extra padding was added to address comfort problems with the elbow being unsupported (Figure 3A). Optional detachable wrist padding was added to address security problems with users with smaller / bigger wrists (Figure 3B). Slanted padding was added to address problems with a sharp edge as well as to make the overall user experience better in comfortable sitting postures (Figure 3C). Prototype 2 had an average assessment value of 8 comfort, 0.2 pain, 1 muscle tension, and 9.2 device security (Figure 4B). After making these changes, the user experience improved significantly (Figure 5). This finding helps us understand that reducing muscle tension and pain in the shoulder and elbow muscles and increasing comfort in terms of securely positioning the wrist is crucial to designing a more sustainable stretching device. In the near future, a third prototype will be built to reassess the device’s comfort in the defined criterias (comfort, pain, muscle tension, device security) and how these criterias are reflected with post-stroke patients, as well as the clinical effectiveness of the stretching devices compared to currently existing physical therapy sessions.

Acknowledgements (Optional): The author would like to acknowledge the support of the National Science Foundation and the Louis Stokes Alliance for Minority Participation grant (NSF 24-563), the Office of Diversity, Equity, and Inclusion of University of Pennsylvania Engineering, as well as the members of the Rehabilitation Robotics Lab of Perelman School of Medicine.